Guys I just bought a 25 cal barrel from a fellow that no longer wanted it. It is a Smith barrel33 in a gain twist. The threads are shot so they need to be cut off and re threaded.

It was originally chambered for 25-06 AI

Is there a particular cartridge that is better suited to a gain twist barrel or can I have it chambered in 257 Roberts?

Thanks Greg

That should be number 3 not 33.
Thanks greg

kinda old idea tried it in 97 but did not seem to be enough improvement over standard shattered conventional bullets and copper fouled the snot out of a barnes x at the muzzle end.

Krieger, Barlein and a few other "cutters" have been showing up on the 100-200-300 yd group game recently. To answer your question, it will do fine as a 257 Roberts.

once you have a "AI chamber it will have to be rechambered to AI if all you do is cut off the threads and rechamber.

Even the .25-06 won't clean up the body taper of the .257 Roberts AI.

If you want a .25-06 chamber you will probably have to cut off the barrel a full 2" or so and then rethread......and you probably don't have that much barrel to work with.

Cut off the threads and rethread and rechamber to .257 Roberts AI is your best option.

Personally....I'd sell the barrel and buy a new one.

forgive the "AI" folks Lord as they know not what they do!

The 6.5 Carcano used a gain twist and from the experience I and others have had it was reasonably accurate. Personally it seems the Roberts NO AI would do just dandy. If the barrel will allowroger

I have two of the few gain-twist barrels that Pac-Nor made awhile back -- both in 30-cal. One is still a blank but the other was chambered in the 30-cal Lzzzeroni Patriot.

Most of the gain-twist barrels I've seen have only a small difference in the rate-of-twist from chamber to crown but the Pac-Nor's I have start out at 50-1 and finish at 10-1 at the muzzle.

Now this is only one barrel but these are some of the things I've discovered.

1) The barrels can be difficult to clean as the brush's tend to skip over the rifleing.

2) It's difficult to get a really smooth bore because of the way it's cut -- Chris at Pac-Nor suggested I use the Tubb's Final Finish process and it worked like a charm -- it's not the slickest, easiest cleaning barrel I have and the process didn't move the throat forward at all.

3) In answer to the questioh about why go to a gain-twist all I can address is mine and the biggest thing is by starting at a 50-1 rate of twist the initial effort needed to move the bullet is less (not imparting as much spin as a standard 10-1 twist) and this allows you to try different powders that wouldn't normally allow
higher velocities with certain rate bullets.

Think about that for a moment. How many times have you have reached max pressure with a certain bullet/poweder combination and still had room in the case for more powder -- reducing this intitial pressure while the bullet leaves the case and starts to be rotated may allow you to utilitze this "excess" capacity with ceratin bullet weighs and powders.

What this means to me is the cartridges that would benefit from a gain-twist like mine would be those that are "slightly over-bore" and that it would have very little effect on a well-balanced cartridge like the 257AI etc.

Without out going into specifics I've been able to apporach 300 Weatherby velocities with a case with much less capacity --- part of this is, I believe, becasue the short-fat Patriot is very efficient at burning powder but also because of the lower initial pressure from the gain-twist barrel. Note that Weatherby velocities are usually report in 26" barrels while mine is 24". Oehler chrono used to measure velocities.

And also remember this is only one barrel.

Some German Artillery, and an M1-A I shot a fair amount had Gain Twist barrels.

Both were pretty effective at long range.

As a follow up to my original post, I know about 2 articles written on the benefits of "gain-twist" rifled barrels.

Both were written by "Mic" McPherson, one of the more thoughful writers. The 1st was in "Precision Shooting" --- April or May of 1999 and the other was in the October issue of "Rifle Shooter" magazine.

I talked to Mic when the 1st article came out and he was quite interested in pursuing the concept but it was right after that he starting publishing articles of his new line of cases and I suspect that took up most of his time.

Mic made a couple of points in his articles that I kind of glossed over in my post.

1) The ones he's shot a variety of bullet weights accurately (I got excellent accuracy with 165, 180 and 200gr Nosler's in my Patriot).

2) You can use faster powders that you would normally expect becasue the gain-twist has a different pressure curve.

3) He thought the most advantage would be realized in cartridges that were well over-bore like the 30-378 Weatherby etc.

In response to a question I received about the velocities I got with my Patriot --- 165gr Nosler Partiton just shy of 3340 fps, 180gr Nosler Partition 3230 fps, and the 200gr Nosler Partition 3110 fps with the 24" barrel discussed above ---- and no signs of excess pressure. Accuracy was easily sub-moa for 3-shot groups for each of the bullet weights.